Kühn K
Coll Relat Res. 1984 Aug;4(4):309-22. doi: 10.1016/s0174-173x(84)80038-2.
The covalent protein structures of the homologous chains alpha 1 (I), alpha 2 (I) and alpha 1 (III) are known. Recently the structure of the alpha 2 (I) gene, at least the number and size of its exons has been almost completely elucidated. About 60% of the pro alpha-chain amino acid sequence is involved in the formation of the collagen triple helix. In the protein a repeating D unit is present which is important for the self assembly of the molecules into fibrils. In the gene, no obvious relationship between the 54 base pairs long exons and the repeating D unit could be found. This led to the conclusion that the region of the pro alpha chains involved in triple helix formation evolved first by repeated tandem duplications of an ancestral 54 base pairs exon and that the D repeat in the protein evolved independently of the exon structure of the gene. However, in other important functional regions of the pro alpha-chains that are not involved in helix formation, there is a good correlation with the gene exon structure.
同源链α1（I）、α2（I）和α1（III）的共价蛋白质结构已为人所知。最近，α2（I）基因的结构，至少其外显子的数量和大小已几乎完全阐明。原α链氨基酸序列约60%参与胶原蛋白三螺旋的形成。在蛋白质中存在一个重复的D单元，它对分子自组装成纤维很重要。在基因中，未发现54个碱基对长的外显子与重复D单元之间有明显关系。由此得出结论，参与三螺旋形成的原α链区域首先通过一个祖先的54个碱基对外显子的重复串联复制而进化，并且蛋白质中的D重复序列独立于基因的外显子结构而进化。然而，在原α链的其他不参与螺旋形成的重要功能区域，与基因外显子结构有良好的相关性。
